/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.solr.search;

import org.apache.lucene.queryParser.ParseException;
import org.apache.lucene.search.Query;
import org.apache.solr.common.params.SolrParams;
import org.apache.solr.common.util.NamedList;
import org.apache.solr.request.SolrQueryRequest;
import org.apache.solr.search.function.BoostedQuery;
import org.apache.solr.search.function.FunctionQuery;
import org.apache.solr.search.function.QueryValueSource;
import org.apache.solr.search.function.ValueSource;

/**
 * Create a boosted query from the input value. The main value is the query to
 * be boosted. <br>
 * Other parameters: <code>b</code>, the function query to use as the boost.
 * <p>
 * Example: <code>{!boost b=log(popularity)}foo</code> creates a query "foo"
 * which is boosted (scores are multiplied) by the function query
 * <code>log(popularity)</code>. The query to be boosted may be of any type.
 * 
 * <p>
 * Example: <code>{!boost b=recip(ms(NOW,mydatefield),3.16e-11,1,1)}foo</code>
 * creates a query "foo" which is boosted by the date boosting function
 * referenced in {@link org.apache.solr.search.function.ReciprocalFloatFunction}
 */
public class BoostQParserPlugin extends QParserPlugin {
	public static String NAME = "boost";
	public static String BOOSTFUNC = "b";

	public void init(NamedList args) {
	}

	@Override
	public QParser createParser(String qstr, SolrParams localParams,
			SolrParams params, SolrQueryRequest req) {
		return new QParser(qstr, localParams, params, req) {
			QParser baseParser;
			ValueSource vs;
			String b;

			@Override
			public Query parse() throws ParseException {
				b = localParams.get(BOOSTFUNC);
				baseParser = subQuery(localParams.get(QueryParsing.V), null);
				Query q = baseParser.getQuery();

				if (b == null)
					return q;
				Query bq = subQuery(b, FunctionQParserPlugin.NAME).getQuery();
				if (bq instanceof FunctionQuery) {
					vs = ((FunctionQuery) bq).getValueSource();
				} else {
					vs = new QueryValueSource(bq, 0.0f);
				}
				return new BoostedQuery(q, vs);
			}

			@Override
			public String[] getDefaultHighlightFields() {
				return baseParser.getDefaultHighlightFields();
			}

			@Override
			public Query getHighlightQuery() throws ParseException {
				return baseParser.getHighlightQuery();
			}

			@Override
			public void addDebugInfo(NamedList<Object> debugInfo) {
				// encapsulate base debug info in a sub-list?
				baseParser.addDebugInfo(debugInfo);
				debugInfo.add("boost_str", b);
				debugInfo.add("boost_parsed", vs);
			}
		};
	}

}
